Do forests reduce erosion? The answer is not as simple as you may think

Authors: Mark Bloomberg, Tim Davies
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2011, Issue N.Z.J.For. 56(4) 2012, pp 16-20, Jan 2012
Publisher: New Zealand Institute of Forestry

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Abstract: Introduction In this article we attempt to reconcile two different perspectives of soil erosion in relation to land cover. From a land-use perspective, there is ample evidence that planting trees reduces erosion; from a geological perspective, however, land-use is irrelevant to longterm erosion rates which are controlled by tectonic uplift and denudation. We show that aspects of the geological viewpoint are indeed relevant to the landuse perspective. Human experience of erosion in NZ The interaction between forests and soil erosion has featured in New Zealand history from the beginning of human settlement. Deforestation by Mäori settlers, mostly achieved by fire, reduced the forested area in New Zealand by about half (McGlone 1989). There is evidence that this deforestation triggered erosion, with tree charcoal preserved in hollows buried by downslope movement of soil and debris (McGlone 1989). Harmsworth and Raynor (2004) state that Mäori were intimately involved with the physical environment and managed natural resources (including forests) within the domain of ritenga—customs and laws regulating behaviour in relation to both people and the environment. King et al. (2007) document Mäori environmental knowledge in relation to natural hazards, but the only landslides mentioned are those triggered by volcanic activity. Neither report a specific Mäori focus on conserving forests as a means to combat soil erosion.

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